Electrowetting display device

ABSTRACT

An electrowetting display device includes a plurality of pixels each including an array substrate, an opposite substrate, and an electrowetting layer. The array substrate includes a base substrate, a barrier wall defining a pixel area, a partition wall partitioning the pixel area into a plurality of sub-pixel areas, a hydrophobic layer disposed in the sub-pixel areas, and an electronic device controlling the electrowetting layer.

CROSS-REFERENCE TO RELATED APPLICATION

This U.S. non-provisional patent application is a continuation of andclaims priority to U.S. patent application Ser. No. 13/765,242, filed onFeb. 12, 2013 Now U.S. Pat. No. 8,854,718 B2, that claims priority toand benefit of Korean Patent Application No. 10-2012-0094448, filed onAug. 28, 2012 in the Korean Intellectual Property Office, the contentsof which are incorporated herein by reference.

BACKGROUND

1. Field of the Invention

The present disclosure relates to an electrowetting display device usingan electrowetting effect for changing displayed images.

2. Description of the Related Art

Various types of flat panel display devices, e.g., the liquid crystaldisplay device, the plasma display device, the organic light emittingdisplay, the field effect display device, the electrophoretic displaydevice, the electrowetting display device, etc., have been widely used.

In general, an electrowetting display device may apply a voltage to afluid, e.g., an aqueous liquid electrolyte, to change a surface tensionof the fluid. Accordingly, the fluid may transmit or reflect lightprovided from an external source so as to display desired images.

SUMMARY

One or more embodiments of the invention may be related to anelectrowetting display device that has satisfactorily high transmittanceand satisfactorily fast response speed.

One or more embodiments of the invention may be related to anelectrowetting display device that includes the following elements: abase substrate, a barrier wall disposed on the base substrate to definea pixel area, a partition wall that partitions the pixel area into aplurality of sub-pixel areas, a hydrophobic layer disposed in thesub-pixel areas, an electrowetting layer disposed in each of thesub-pixels and including a first fluid and a second fluid, which areimmiscible with each other, and an electronic device disposed in thepixel area and configured for applying a voltage to the electrowettinglayer to control the electrowetting layer. The second fluid haselectrical conductivity and/or polarity.

The electrowetting display device further includes an opposite substrateoverlapping the base substrate. The electronic device includes aswitching device provided to correspond to the pixel area, a firstelectrode connected to the switching device and covering at least aportion of each of the sub-pixels, and a second electrode disposed onthe opposite substrate and applied with a common voltage to generate anelectric field in cooperation with the first electrode.

The electrowetting display device further includes a reference electrodedisposed on the base substrate, spaced (and electrically insulated) fromthe first electrode, and applied with a reference voltage. The referencevoltage has a same level as the common voltage. The reference electrodecovers at least a portion of the switching device.

The pixel area includes a first sub-pixel area and a second sub-pixelarea.

According to the above, the electrowetting display device may providesatisfactory display quality. The electrowetting display device may bemanufactured using a simple and low-cost manufacturing process, so thatmanufacturing time and cost of the electrowetting display device maybeminimized.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other advantages of the present invention will becomereadily apparent by reference to the following detailed description whenconsidered in conjunction with the accompanying drawings wherein:

FIG. 1A is a plan view illustrating an electrowetting display deviceaccording to one or more embodiments of the present invention;

FIG. 1B is a cross-sectional view taken along a line I-I′ indicated inFIG. 1A;

FIG. 2 is a circuit diagram illustrating an active matrix type pixelincluding a switching device;

FIG. 3A is a plan view illustrating an electrowetting display deviceaccording to one or more embodiments of the present invention;

FIG. 3B is a cross-sectional view taken along a line II-II′ indicated inFIG. 3A;

FIG. 4A is a plan view illustrating an electrowetting display deviceaccording to one or more embodiments of the present invention;

FIG. 4B is a cross-sectional view taken along a line indicated in FIG.4A;

FIG. 5A is a plan view illustrating an electrowetting display deviceaccording to one or more embodiments of the present invention;

FIG. 5B is a cross-sectional view taken along a line IV-IV′ indicated inFIG. 5A;

FIG. 6A is a plan view illustrating an electrowetting display deviceaccording to one or more embodiments of the present invention;

FIG. 6B is a cross-sectional view taken along a line V-V′ indicated inFIG. 6A;

FIG. 7 is a cross-sectional view illustrating an electrowetting displaydevice according to one or more embodiments of the present invention;

FIGS. 8A to 8C are plan views illustrating arrangements of pixels andpositions of a partition wall;

FIG. 9A is a plan view illustrating an electrowetting display device infurther detail according to one or more embodiments of the presentinvention;

FIG. 9B is a cross-sectional view taken along a line VI-VI′ indicated inFIG. 9B;

FIG. 10A is a plan view illustrating an electrowetting display device infurther detail according to one or more embodiments of the presentinvention; and

FIG. 10B is a cross-sectional view taken along a line VII-VII′ indicatedin FIG. 10B.

DETAILED DESCRIPTION

In the specification, when an element or layer is referred to as being“on”, “connected to”, or “coupled to” another element or layer, it canbe directly on, directly connected, or directly coupled to the otherelement or layer, or intervening elements or layers may be present. Incontrast, when an element is referred to as being “directly on,”“directly connected to” or “directly coupled to” another element orlayer, there are no intervening elements or layers (except possibleenvironmental elements such as air) present between the two elements ortwo layers. Like numbers may refer to like elements in thespecification. As used herein, the term “and/or” may include any and allcombinations of one or more of the associated listed items.

Although the terms first, second, etc. may be used herein to describevarious elements, components, regions, layers and/or sections, theseelements, components, regions, layers and/or sections should not belimited by these terms. These terms may be used to distinguish oneelement, component, region, layer or section from another region, layeror section. Thus, a first element, component, region, layer or sectiondiscussed below could be termed a second element, component, region,layer or section without departing from the teachings of the presentinvention. The description of an element as a “first” element may notrequire or imply the presence of a second element or other elements. Theterms first, second, etc. may also be used herein to differentiatedifferent categories of elements. For conciseness, the terms first,second, etc. may represent first-type (or first-category), second-type(or second-category), etc., respectively.

Spatially relative terms, such as “beneath”, “below”, “lower”, “above”,“upper”, etc. may be used herein for ease of description to describe oneelement or feature's relationship to another element(s) or feature(s) asillustrated in the figures. The spatially relative terms are intended toencompass different orientations of the device in use or operation inaddition to the orientation depicted in the figures. For example, if thedevice in the figures is turned over, elements described as “below” or“beneath” other elements or features would then be oriented “above” theother elements or features. Thus, the term “below” can encompass both anorientation of above and below. The 5 device may be otherwise oriented(rotated 90 degrees or at other orientations) and the spatially relativedescriptors used herein interpreted accordingly.

The terminology used herein is for the purpose of describing particularembodiments and is not intended to be limiting of the invention. As usedherein, the singular forms, “a”, “an”, and “the” may include the pluralforms as well, unless the context clearly indicates otherwise. The terms“includes” and/or “including”, when used in this specification, specifythe presence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this invention belongs. It will befurther understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art andwill not be interpreted in an idealized or overly formal sense unlessexpressly so defined herein.

FIG. 1A is a plan view illustrating an electrowetting display deviceaccording to one or more embodiments of the present invention. FIG. 1Bis a cross-sectional view taken along a line I-I′ indicated in FIG. 1A.

The electrowetting display device may include a plurality of pixelsarranged in a matrix form. The pixels may have analogous configurations,functions, and/or features. FIGS. 1A and 1B illustrate a pixel PXL ofthe pixels as an example.

Referring to FIGS. 1A and 1B, the pixel PXL includes (a portion of) anarray substrate, (a portion of) an opposite substrate, and anelectrowetting layer that may include a first fluid FL1 (or 5 first-typefluid FL1) and a second fluid FL2 (or second-type fluid FL2). The arraysubstrate includes a first base substrate BS1, a first electrode EL1, aswitching device (not shown), a barrier wall WL, a partition wall PTN,and a hydrophobic layer HPL. The opposite substrate includes a secondbase substrate BS2, a second electrode EL2, and a column spacer CS. Thefirst electrode EL1, the switching device, and the second electrode EL2may serve as an electronic device configured to drive the electrowettinglayer fluids FL1 and FL2.

The electrowetting display device includes a front surface on which animage is displayed and a rear surface opposite the front surface. Aviewer may perceive the image displayed on the electrowetting displaydevice in front of the front surface. In one or more embodiments, anouter surface of the second base substrate BS2 (i.e., an upper surfaceof the second base substrate BS2 in FIG. 1) is referred to as the frontsurface or the upper surface, and an opposite surface to the front orupper surface is referred to as the rear surface or a lower surface.Nevertheless, the positions of the front surface and the rear surfaceshould not be limited thereto or thereby. The positions of the frontsurface and the rear surface may be changed depending on an operationmode of the electrowetting display device, such as a reflective mode, atransmissive mode, a transflective mode, etc. The electrowetting displaydevice may be a segmented display type device in which the imageincludes and/or is built up of segments. The electrowetting displaydevice may be an active matrix driving display device or a passivematrix driving display device.

Each of the first base substrate BS1 and the second base substrate BS2may be formed as a single body to be commonly shared by the pixels PXLor may include a plurality of substrate members. Each pixel PXL mayinclude a portion of each base substrate, may include a portion of abase substrate and a substrate member, or may include two oppositesubstrate members. The first base substrate BS1 and/or the second basesubstrate BS2 may be, but not limited to, a transparent insulator, suchas a glass element or a polymer element (e.g., a plastic element). Inone or more embodiments, at least one of the first base substrate BS1and the second base substrate BS2 may be a plastic substrate. In one ormore embodiments, at least one of the first base substrate BS1 and thesecond base substrate BS2 may include one or more of a polyethyleneterephthalate (PET) element, a fiber reinforced plastic (FRP) element,and a polyethylene naphthalate (PEN) element. The first base substrateBS1 and/or the second base substrate BS2 may be rigid or may beflexible.

The electrowetting display device may include a plurality of pixelareas, wherein each pixel area of the plurality of pixel areas maycorrespond to a pixel of the plurality of pixels. The barrier wall WLmay define and/or surround a pixel area PA corresponding to the pixelPXL. The barrier wall WL absorbs light in a visible wavelength range andhas a black color. Accordingly, the barrier wall WL may prevent imagecrosstalk between adjacent pixels and/or may prevent light from leakingbetween adjacent pixels.

The area of the pixel area PA defined by the barrier wall WL has beenrepresented by dotted lines in FIG. 1A. In one or more embodiments, thebarrier wall WL is formed on and/or protrudes from the first basesubstrate BS1. The first base substrate BS1 (a barrier layer BRL, and/orthe hydrophobic layer HPL) and the barrier wall WL may define a space ineach pixel area PA.

The pixel area PA may have one of various shapes in accordance with theshape of the pixel PXL. In one or more embodiments, as illustrated inFIG. 1A, the pixel area PA may have a rectangular shape. In one or moreembodiments, the pixel area PA may have a polygonal shape (that may notbe rectangular).

The partition wall PTN is provided in the pixel area PA to divide thepixel area PA into a plurality of sub-pixel areas, wherein eachsub-pixel area of the plurality of sub-pixel areas may include asub-space for containing a set of the first fluid FL1 (or a set of thefirst-type fluid FL1), and wherein the space defined by the first basesubstrate BS1 and the barrier wall WL include the subspaces. In one ormore embodiments, the plurality of sub-pixel areas may include twosub-pixel areas, e.g., a first sub-pixel area SPA1 and a secondsub-pixel area SPA2, as illustrated in in FIGS. 1A and 1B. The firstsub-pixel area SPA1 may include a first sub-space containing a first setof the first fluid; the second sub-pixel area SPA2 may include a secondsub-space containing a second set of the first fluid. The barrier wallWL may surround both the first sub-space and the second sub-space. Thepartition wall PTN may be disposed between the first sub-space and thesecond sub-space. In one or more embodiments, the pixel area PA may bedivided into three or more sub-pixel areas. The sub-pixel areaspartitioned by the partition wall PTN may have the same shape and/or mayhave the same size. In one or more embodiments, the pixel area PA has arectangular shape, the partition wall PTN is disposed a center portionof the rectangular shape and is substantially parallel to at least oneof the four sides of the rectangular shape, and thus the first sub-pixelarea SPA1 and the second sub-pixel area SPA2 may have the same shape andmay have the same size. As illustrated in FIG. 1A, the pixel area PA hasthe rectangular shape with long sides and short sides, and the partitionwall PTN is disposed at the middle between the short sides correspondingto center portions of the long sides. Both end pmlions of the partitionwall PTN are connected to the barrier wall WL, so that each of the firstsub-pixel area SPA1 and the second sub-pixel area SPA2 is closed. Thepartition wall PTN may protrude from the barrier wall WL and/or may beintegrally formed with the barrier wall WL.

The barrier wall WL and the partition wall PTN may restrict movement ofat least one of the first fluid FL1 and the second fluid FL2.

In one or more embodiments, the barrier wall WL and/or the partitionwall PTN may have a height that is sufficient to prevent the first fluidFL1 from diffusing to adjacent pixels and/or diffusing to an adjacentsub-pixel area when the electronic device is operated. In one or moreembodiments, the height of the partition wall PTN with respect to thefirst substrate BS1 may be substantially equal to the height of thebarrier wall WL with respect to the first substrate BS1.

In one or more embodiments, at least one surface of the barrier wall WLand at least one surface of the partition wall PTN has property that isincompatible with the property of the first fluid FL1 or the secondfluid FL2 in order to restrict movement of the first fluid FL1 or thesecond fluid FL2. In one or more embodiments, the first fluid FL1 hashydrophobicity, and at least one surface of the barrier wall WL and atleast one surface of the partition wall PTN have hydrophilicity that isexclusive (and incompatible) to the hydrophobicity, for restrictingmovement of the first fluid FL1. In one or more embodiments, an uppersurface of the barrier wall WL that is substantially parallel to thefirst base substrate BS1 and side surfaces of the barrier wall WL thatare perpendicular to (and/or not parallel to) the upper surface of thebarrier wall WL and the first base substrate BS1 (and/or parallel to thepartition wall PTN) may have the hydrophilicity. In one or moreembodiments, the side surfaces of the barrier wall WL may havehydrophobicity, and the upper surface of the barrier wall WL may havethe hydrophilicity. In one or more embodiments, an upper surface of thepartition wall PTN that is substantially parallel to the first basesubstrate BS1 and side surfaces of the partition wall PTN that areperpendicular to (and/or not parallel to) the upper surface of thepartition wall PTN and the first base substrate BS1 (and/or parallel tothe barrier wall WL) may have the hydrophilicity. In one or moreembodiments, the side surfaces the partition wall PTN may havehydrophobicity, and the upper surface of the partition wall PTN may havethe hydrophilicity. Thus, the barrier wall WL and the partition wall PTNmay not be easily wetted by the first fluid FL1, and the first fluid FL1may not enter an adjacent pixel area PA or enter an adjacent sub-pixelarea even though the height of the barrier wall WL and the height of thepartition wall PTN may be lower than the maximum height of the firstfluid FL1 in one or more embodiments.

The column spacer CS may be disposed on the second base substrate BS2and/or may protrude from the second base substrate BS2. The columnspacer CS is located at a position corresponding to the barrier wall WL,and a contact surface of the column spacer CS may directly contact thebarrier wall WL. The column spacer CS maintains a distance (hereinafterreferred to as a cell gap) between the first base substrate BS1 and thesecond base substrate BS2 (or between the barrier layer BRL or thehydrophobic layer HPL and the second electrode EL2) in cooperation withthe barrier wall WL. The column spacer CS has a height greater than thatof the barrier wall WL. The cell gap is set to allow the first fluid FL1and the second fluid FL2 provided in each pixel area PA to smoothly movein the pixel area PA. Particularly, the cell gap is set to have a valuegreater than the maximum height of the first fluid FL1, such that thefirst fluid FL1 may not contact the second base substrate BS2 (and/orthe second electrode EL2) while moving in the pixel area PA.

The hydrophobic layer HPL is provided in the sub-pixel areas defined bythe barrier wall WL and the partition wall PTN and is disposed on thefirst base substrate BS1. The hydrophobic layer HPL may be disposedbetween at least two portions of the barrier wall WL in a pixel PXL. Inone or more embodiments, a hydrophobic layer HPL may be disposed in asub-space and disposed between at least a portion of the barrier wall WLand the partition wall PTN. In one or more embodiments, a hydrophobiclayer HPL may overlap the barrier wall WL and/or may overlap thepartition wall PTN.

The hydrophobic layer HPL may include a compound that contains fluorineatoms. In one or more embodiments, the fluorine-compound may be apolymer compound represented by one or more of the following chemicalformulas: -CxFy-, CxFyHz-, -CxFyCzHp-, -CxFyO—, -CxFyN(H)—, etc.,wherein each of x, y, z, p, n, and m is an integer number equal to orlarger than 1. In one or more embodiments, the fluorine-containingcompound may be an amorphous fluorine compound.

The hydrophobic layer HPL may have permeability or reflectiveness forlight. In one or more embodiments, the hydrophobic layer HPL hasreflectiveness, such that light provided from a light source andincident on the hydrophobic layer HPL may be totally reflected by thehydrophobic layer HPL. In one or more embodiments, the hydrophobic layerHPL may have the white color. In one or more embodiments, thehydrophobic layer HPL may absorb a portion of light corresponding to aspecific wavelength and may reflect another portion of the light todisplay a specific color.

The barrier layer BRL may be disposed between the first base substrateBS1 and the hydrophobic layer HPL and/or may be disposed between thefirst base substrate BS1 and the barrier wall WL. The barrier layer BRLmay prevent at least one of the electrowetting layer fluids FL1 and FL2from contacting a portion of the electronic device, such as the firstelectrode EL1. The barrier layer BRL may have a single-layer structureor a multi-layer structure, e.g., a double-layer structure.

The electrowetting layer fluids FL1 and FL2 are disposed in the space(and the sub-spaces) defined by the barrier wall WL (and the partitionwall PTN) with at least one of the first base substrate BS1 and thesecond base substrate BS2 and/or one or more elements disposed on atleast one of the first base substrate BS1 and the second base substrateBS2. The electrowetting layer fluids FL1 and FL2 may include the firstfluid FL1 (or first-type fluid FL1) and the second fluid FL2 (orsecond-type fluid FL2). The first fluid FL1 and the second fluid FL2 areimmiscible with each other. The second fluid FL2 may have electricalconductivity and/or polarity. For example, the second fluid FL2 mayinclude at least one of potassium chloride solution, sodium chloride,water, and ethyl alcohol. The second fluid FL2 may be transparent or mayhave a color. As an example, the second fluid FL2 may have the whitecolor. As another example, the second fluid FL2 may absorb or reflectlight with one or more particular wavelengths.

The first fluid FL1 may be electrically nonconductive. In one or moreembodiments, the first fluid FL1 may include at least one of alkane(e.g., hexadecane) and oil (e.g., silicone oil). In one or moreembodiments, the first fluid FL1 may include oil that is notelectrically conductive, and the second fluid FL2 may be an electrolytesolution having electrical conductivity.

The first fluid FL1 may absorb at least a portion of the opticalspectrum of a visible light. The first fluid FL1 may transmit theremaining portion of the optical spectrum, so that the first fluid FL1may display a color. The first fluid FL1 may include pigment particlesor dyes for displaying the color. According to one or more embodiments,the first fluid FLI may be colored with a black dye. Therefore, thefirst fluid FL1 may absorb substantially the entire optical spectrum ofan incident light. In one or more embodiments, the second fluid FL2 mayreflect the optical spectrum.

An electronic device is provided in each pixel PXL and applies anelectric potential difference between the electrodes EL1 and EL2 tocontrol the electrowetting layer fluids FL1 and FL2.

Among the parts of the electronic device, the first electrode EL1 isdisposed on the first base substrate BS1, and the second electrode EL2is disposed on the second base substrate BS2. The first electrode EL1may be disposed between the first base substrate BS1 and the hydrophobiclayer HPL and may overlap (and partially cover) the first sub-pixel areaSPA1 and the second sub-pixel area SPA2. The first electrode EL1 may beintegrally formed as a single unitary and individual unit tosubstantially simultaneously cover a portion of the first sub-pixel areaSPA1 and a portion of the second sub-pixel area SPA2. The firstelectrode EL1 may overlap the partition wall PTN.

In one or more embodiments, the electrowetting display device is atransmission type electrowetting display device, and the first electrodeEL1 may include a transparent conductive material, such as indium tinoxide (ITO), indium zinc oxide (IZO), or indium tin zinc oxide (ITZO).In one or more embodiments, the electrowetting display device is areflection type electrowetting display device, and the first electrodeEL1 may include a reflective conductive material, such as a metalmaterial, e.g., aluminum.

The first electrode EL1 may have a shape that is the same as or similarto that of the pixel area PA, but the shape of the first electrode EL1should not be limited thereto or thereby. In the plan view of theelectrowetting display device, the first electrode EL1 may partiallyoverlap the pixel area PA without completely overlapping the pixel areaPA, such that the first electrode EL1 does not overlap a portion of thepixel area PA, e.g., a corner portion of the pixel area PA. The firstelectrode EL1 may have an area smaller than that of the pixel area PA soas not to cover the portion of the pixel area PA. A space in the pixelarea PA corresponding to the portion of the PA not covered or overlappedby the first electrode EL1 may not be substantially affected by thevoltage applied to the first electrode EL1, and thus the first fluid FL1may be substantially gathered to the space in the pixel area that is notoverlapped by the first electrode EL1; the space in the pixel area maybe considered a collection point for the first fluid FL1. In FIG. 1A, asubstantial portion of the first fluid FL1 is gathered to the portion ofthe pixel area PA between the first electrode EL1 and the barrier wallWL in the plan view of the electrowetting display device. In one orembodiments, the first electrode Ell may have a shape that is differentfrom that the shape of the first electrode EL1 illustrated in FIG. 1A;accordingly, the collection point may be located at different positions.

The second electrode EL2 may be integrally formed as a single unitaryand individual unit to cover all the pixels PXL of the electrowettingdisplay device. In one or more embodiments, the second electrode EL2 mayinclude a plurality of separate electrode members respectivelycorresponding to the pixels PXL, and the electrode members of the secondelectrode EL2 may be electrically connected to each other. The secondelectrodes EL2 may make contact with the second fluid FL2 to beconnected to each other. In one or more embodiments, the secondelectrode EL2 may include a transparent conductive material, such asindium tin oxide (ITO), indium zinc oxide (IZO), or indium tin zincoxide (ITZO).

In one or more embodiments, the first electrode EL1 and the secondelectrode EL2 are respectively disposed on the first base substrate BS1and the second base substrate BS2, but they should not be limitedthereto or thereby. In one or more embodiments, both the first electrodeEL1 and the second electrode EL2 may be disposed on the first basesubstrate BS1, wherein the second electrode EL2 may be provided at oneor more sides of the first electrode EL1 and may be electricallyinsulated from the first electrode EL1. For example, the first electrodeEL1 may be provided in a portion of the pixel area PA surrounded by thebarrier wall WL, and the second electrode EL2 may be provided in theother portion of the pixel area PA and may be insulated from the firstelectrode EL1 by the barrier wall WL. In one or more example, the firstelectrode EL1 may overlap the pixel area PA and may be surrounded by thebarrier wall WL, and the second electrode EL2 may be provided on a sidesurface of the barrier wall WL and may be insulated from the firstelectrode EL1 by the barrier wall WL.

The switching device (not illustrated) is disposed on the first basesubstrate BS1 and electrically connected to the first electrode EL1. Thepixel PXL is in an ON-state when different voltages are respectivelyapplied to the first electrode EL1 and the second electrode EL2. Thevoltage difference may result in one or more electrostatic forces, e.g.,one or more attraction forces and/or one or more repulsion forces, thatmay move the second fluid FL2 to the first electrode EL1, and thus thefirst fluid FL1 (which substantially covers the hydrophobic layer HPL inthe sub-space associated with the first fluid FL1) is pushed away from asubstantial portion of the hydrophobic layer HPL to a smaller portion ofthe hydrophobic layer HPL at the barrier wall WL, which surrounds thehydrophobic layer HPL, such that the first fluid FL1 may accumulate atthe collection point, which does not substantially overlap the firstelectrode EL1. When the first fluid FL1 is completely pushed to thebarrier wall WL by the second fluid FL2, the first fluid FL1 may have adrop shape (at least in the cross-sectional view of the electrowettingdisplay device) as illustrated by a hatched drop shape (or drop shapewith hatching) in FIG. 1B. The first fluid FL1 has the maximum height ofthe first fluid FL1 when the pixel PXL is in the ON-state. Accordingly,the hydrophobic layer HPL of the pixel PXL only partially or minimallycovered by the first fluid FL1, and a substantial portion of thehydrophobic layer HPI may be exposed.

When the difference between the voltages applied to the electrodes EL1and EL2 returns to about zero volts and/or is below a threshold value,the pixel PXL returns to an OFF-state, so that the first fluid FL1substantially covers the hydrophobic layer HPL again since theelectrostatic force caused by the electric potential differencedisappears. In FIG. 1B, the upper surface of the first fluid FL1 isrepresented by a dashed line when the pixel PXL is in the OFF-state.

In one or more embodiments, the first fluid FL1 and the second fluid FL2are substantially simultaneously controlled in the first sub-pixel areaSPA1 and the second sub-pixel area SPA2 in accordance with the ON-stateand the OFF-state of the pixel PXL. As a result, the first fluid FL1serves as an optical switch that is able to be electrically controlledin each pixel PXL.

FIG. 2 is a circuit diagram illustrating an active matrix type pixelincluding a switching device.

The switching device includes a transistor TR, a first capacitor CAP1,and a second capacitor CAP2 configured to control the electrowettinglayer fluids FL1 and FL2 in the pixel area PA in response to a gatesignal and/or an image signal. In one or more embodiments, each pixelmay include one or more transistors. FIG. 2 illustrates a transistor TRin the pixel as an example.

The transistor TR includes a gate electrode, a source electrode, and adrain electrode. The transistor TR is electrically connected to a linepmt. The line part includes a gate line GL and a data line DL, which areelectrically connected to the transistor TR. The gate electrode isconnected to the gate line GL, the source electrode is connected to thedata line DL, and the drain electrode is connected to the capacitorsCAP1 and CAP2. The first capacitor CAP1 is an electrowetting capacitorthat may include the first electrode EL1, the second electrode EL2, andat least a fluid provided between the first electrode EL1 and the secondelectrode EL2. The second electrode EL2 may receive a common voltageVcom that may be applied to the second fluid FL2 since the second fluidFL2 may contact the second electrode EL2. The second capacitor CAP2 is astorage capacitor configured to include the drain electrode (and/or thefirst electrode EL1), a storage electrode, and an insulating layerdisposed between the drain electrode (and/or the first electrode EL1)and the storage electrode. The storage electrode is connected to astorage line STL.

The voltage applied to the first electrode EL1 is set by the data lineDL while the transistor TR is turned on. When a gate signal is appliedto the gate line GL, the transistor TR is turned on, and thus thevoltage applied to the data line DL is applied to the capacitors CAP1and CAP2. After the data voltage is applied to the first electrode EL1,the data voltage remains in the capacitors due to a coupling capacitanceof one or more of the capacitors CAP1 and CAP2 so as to maintain thestate of the pixel PXL until the voltage is refreshed.

An electrowetting display device having the structures discussed withreference to FIGS. 1A, 1B, and 2 may have a satisfactorily fast responsespeed and a satisfactorily high light transmittance. In anelectrowetting display device, if the pixel area is large (e.g., largerthan a threshold area size associated with the fluid dynamic of theelectrowetting layer fluids), the colored fluid (i.e., the first fluidFL1) may not sufficiently and timely cover the pixel area when the pixelis changed from the ON-state to the OFF-state. On the other hand, if thepixel area is small (e.g., smaller than the threshold area size), thelight transmittance of the electrowetting display device is reduced bythe switching device provided in each pixel. In contrast, according toone or more embodiments, the light transmittance reduction caused by thepartition wall PTN may be less significant than the light transmittancereduction that may be caused by a switching device, and the responsespeed may be sufficiently fast since a movement distance of the firstfluid is substantially short when the pixel PXL is changed from theON-state to the OFF-state or is changed from the OFF-state to theON-state. Advantageously, the electrowetting display device may have asatisfactorily high light transmittance and a satisfactorily fastresponse speed.

FIG. 3A is a plan view illustrating an electrowetting display deviceaccording to one or more embodiments of the present invention, and FIG.3B is a cross-sectional view taken along a line II-II′ indicated in FIG.3A. In one or more embodiments, the collection point for the first fluidis disposed adjacent to the center portion of the pixel, i.e., disposedat a position adjacent to the partition wall.

In FIGS. 3A and 3B, the same reference numerals may denote elements thatare analogous to or identical to elements illustrated in FIGS. 1A and1B, and detailed descriptions of analogous or identical elements may beomitted.

Referring to FIGS. 3A and 3B, the pixel PXL includes (a portion of) anarray substrate, (a portion of) an opposite substrate, andelectrowetting layer fluids, e.g., a first fluid FL1 and a second fluidFL2. The array substrate includes a first base substrate BS1, a firstelectrode EL1, a reference electrode RE, a switching device (not shown),a barrier wall WL, a partition wall PTN, and a hydrophobic layer HPL.The opposite substrate includes a second base substrate BS2, a secondelectrode EL2, and a column spacer CS. The first electrode EL1, thereference electrode RE, the switching device, and the second electrodeEL2 may serve as an electronic device configured to drive theelectrowetting layer fluids FL1 and FL2.

An electronic device is provided in each pixel PXL and applies anelectric potential difference between the electrodes EL1 and EL2 tocontrol the electrowetting layer fluids FL1 and FL2.

Among the parts of the electronic device, the first electrode EL1 andthe reference electrode RE are disposed on the first base substrate BS1,and the second electrode EL2 is disposed on the second base substrateBS2.

The first electrode EL1 is disposed between the first base substrate BS1and the hydrophobic layer HPL and covers a portion of the firstsub-pixel area SPA1 and a portion of the second sub-pixel area SPA2. Anouter portion of the first electrode EL1 may overlap the barrier wall WLto prevent the corresponding first fluid FL1 from being collectedadjacent to the barrier wall WL. The first electrode EL1 has a throughopening (or through hole) positioned between the first base substrateBS1 and the partition wall PTN; material of the first electrode EL1 isnot formed in the through opening. The through opening may be partiallyor completely surrounded by the material of the first electrode EL1 andmay be rectangular in the plan view of the electrowetting displaydevice.

As illustrated in FIG. 3A, the first electrode EL1 may be integrallyformed as a single unitary unit disposed in the first sub-pixel areaSPA1 and the second sub-pixel area SPA2. In one or more embodiments, thefirst electrode EL1 is not required to be integrally formed as a singleunitary unit as long as the portion of the first electrode EL1 disposedin the first sub-pixel area SPA1 and the portion of the first electrodeEL1 disposed in the second sub-pixel area SPA2 are electricallyconnected to each other and/or as long as the portion of the firstelectrode EL1 disposed in the first sub-pixel area SPA1 and the portionof the first electrode EL1 disposed in the second sub-pixel area SPA2are substantially simultaneously operated by the switching device.

The reference electrode RE may be spaced from the first electrode EL1.In one or more embodiments, the reference electrode RE may be spacedfrom the first electrode EL1 and may be located inside the opening ofthe first electrode EL1.

The reference electrode RE may be electrically insulated from the firstelectrode EL1 and may be applied with a reference voltage that may beindependent of the voltage applied to the first electrode EL1. Thereference voltage applied to the reference electrode RE has a level thatis substantially equal to level of the common voltage applied to thesecond electrode EL2. Accordingly, there may be substantially noelectric potential difference between the reference electrode RE and thesecond electrode EL2.

The reference electrode RE is disposed on the same layer as and formedof the same material as the first electrode EL1. Therefore, the firstelectrode EL1 and the reference electrode RE may be formed in a singleprocess. In one or more embodiments, the electrowetting display deviceis a transmission type electrowetting display device, and the firstelectrode EL1 and the reference electrode RE may include a sametransparent conductive material, such as indium tin oxide (ITO), indiumzinc oxide (IZO), or indium tin zinc oxide (ITZO). In one or moreembodiments, the electrowetting display device is a reflection typeelectrowetting display device, and the first electrode EL1 and referenceelectrode RE may include a same reflective conductive material, such asa metal material, e.g., aluminum.

As illustrated in FIGS. 3A and 3B, the reference electrode RE maypartially overlap the partition wall PTN. In the plan view of theelectrowetting display device, portions of the reference electrode REthat do not overlap the partition wall PTN are located at two sides ofthe partition wall PTN and are symmetrical with respect to the partitionwall PTN to allow two sets of the first fluid FL1 to be gathered to thetwo sides of the partition wall PTN.

The switching device is disposed on the first base substrate BS1 and isconnected to the first electrode EL1.

The pixel PXL is in the ON-state when a voltage that is different fromeach of the reference voltage and the common voltage is applied to thefirst electrode EL1. The electric potential difference between the firstand second electrodes EL1 and EL2 and the electric potential differencebetween the first electrode EL1 and the reference electrode RE mayresult in one or more electrostatic forces, e.g., one or more attractionforces and/or one or more repulsion forces, that may move the secondfluid FL2 to the first electrode EL1. Since substantially no voltagelevel difference exists between the second electrode EL2 and thereference electrode RE, no substantial electrostatic forces act betweenthe second fluid FL2 and the second electrode EL2 and between the secondfluid FL2 and the reference electrode RE. Accordingly, the second fluidFL2 covers the first electrode EL1 to push away the first fluid FL1 tothe reference electrode RE and the partition wall PTN. As a result, theupper surface of the reference electrode RE may correspond to thecollection point for the first fluid FL1. In the one or moreembodiments, since the reference electrode RE overlaps the two sides ofthe partition wall PTN and overlaps the partition wall PTN, the firstfluid FL1 is gathered to the areas immediately adjacent to the partitionwall PTN, e.g., the center portion of the pixel area PA. When the firstfluid FL1 is completely pushed to the partition wall PTN and overlapsthe reference electrode RE, the first fluid FL1 may have a drop shape(at least in the cross-sectional view of the electrowetting displaydevice) as illustrated by a hatched drop shape in FIG. 3B. The firstfluid FL1 has the maximum height of the first fluid FL1 when the pixelPXL is in the ON-state.

When the difference between the voltage applied to the first electrodeEL1 and each of the voltages applied to the reference electrode RE andthe second electrode EL2 returns to about zero volts and/or is below athreshold value, the pixel PXL returns to an OFF-state, so that thefirst fluid FL1 substantially covers the hydrophobic layer HPL againsince the electrostatic force caused by the electric potentialdifference disappears. Accordingly, the first fluid FL1 may serve as anoptical switch that may be electrically controlled in each pixel PXL.

In an electrowetting display device having the structures discussed withreference to FIGS. 3A and 3B, movement and restitution of the fluids maybe substantially efficient since the collection of the first fluid iscontrolled using the electric potential difference. Thus, the responsespeeds of the ON- and OFF-states of the pixel may be satisfactorilyfast, and non-closing of the first fluid FL1 may be prevented.Advantageously, reproducibility and quality of displayed images may besatisfactory.

FIG. 4A is a plan view illustrating an electrowetting display deviceaccording to one or more embodiments of the present invention, and FIG.4B is a cross-sectional view taken along a line indicated in FIG. 4A.

Referring to FIGS. 4A and 4B, the pixel PXL includes (a portion of) anarray substrate, (a portion of) an opposite substrate, andelectrowetting layer fluids, e.g., a first fluid FL1 and a second fluidFL2. The array substrate includes a first base substrate BS1, a firstelectrode EL1, a reference electrode RE, a switching device (not shown),a barrier wall WL, a partition wall PTN, and a hydrophobic layer HPL.The opposite substrate includes a second base substrate BS2, a secondelectrode EL2, and a column spacer CS. The first electrode EL1, thereference electrode RE, the switching device, and the second electrodeEL2 may serve as an electronic device configured to drive theelectrowetting layer fluids FL1 and FL2.

An electronic device is provided in each pixel PXL and applies anelectric potential difference between the electrodes EL1 and EL2 tocontrol the electrowetting layer fluids FL1 and FL2.

Among the parts of the electronic device, the first electrode EL1 andthe reference electrode RE are disposed on the first base substrate BS1,and the second electrode EL2 is disposed on the second base substrateBS2.

The first electrode EL1 is disposed between the first base substrate BS1and the hydrophobic layer HPL and covers a portion of the firstsub-pixel area SPA1 and a portion of the second sub-pixel area SPA2. Inthe plan view of the electrowetting display device, the first electrodeEL1 has a rectangular shape, which may be similar to the shape of thepixel area PA, and two end portions of the first electrode EL1 in alongitudinal direction (or length direction) are spaced from the barrierwall WL. Two end portions of the first electrode EL1 in a widthdirection (perpendicular to the length direction) overlap the barrierwall WL, as illustrated in FIG. 4A.

As illustrated in FIG. 4A, the first electrode EL1 may be integrallyformed as a single unitary unit disposed in the first sub-pixel areaSPA1 and the second sub-pixel area SPA2, and the partition wall PTN mayoverlap the first electrode EL1. In one or more embodiments, the firstelectrode EL1 is not required to be integrally formed as a singleunitary unit as long as the portion of the first electrode EL1 disposedin the first sub-pixel area SPA1 and the portion of the first electrodeEL1 disposed in the second sub-pixel area SPA2 are electricallyconnected to each other and/or as long as the portion of the firstelectrode EL1 disposed in the first sub-pixel area SPA1 and the portionof the first electrode EL1 disposed in the second sub-pixel area SPA2are substantially simultaneously operated by the switching device.

The reference electrode RE is spaced from the first electrode EL1. Inone or more embodiments, the reference electrode RE is spaced from thetwo end portions of the first electrode EL1 in the longitudinaldirection (or length direction). The reference electrode RE may contactand/or overlap the barrier wall WL.

The reference electrode RE may be electrically insulated from the firstelectrode EL1 and may be applied with a reference voltage that may beindependent of the voltage applied to the first electrode EL1. Thereference voltage applied to the reference electrode RE has a level thatis substantially equal to level of the common voltage applied to thesecond electrode EL2. Accordingly, there may be substantially noelectric potential difference between the reference electrode RE and thesecond electrode EL2.

The reference electrode RE is disposed on the same layer as and formedof the same material as the first electrode EL1. Therefore, the firstelectrode EL1 and the reference electrode RE may be formed in a singleprocess.

The reference electrode RE may overlap the barrier wall WL and mayoverlap a pixel area PA of a previous pixel row and a pixel area PA of apresent pixel row. Portions of the reference electrode RE may be atedges of a pixel area PA and may contact the barrier wall WL.

In the plan view of the electrowetting display device, two portions ofthe reference electrode RE that are located at two ends of the barrierwalls WL have be symmetrical with respect to the barrier wall WL.

The switching device is disposed on the first base substrate BS1 and isconnected to the first electrode EL1.

The pixel PXL is in the ON-state when a voltage that is different fromeach of the reference voltage and the common voltage is applied to thefirst electrode EL1. When the pixel PXL is in the ON-state, the secondfluid FL2 substantially covers the first electrode EL1 and pushes thefirst fluid FL1 to the reference electrode RE and the barrier wall WL.As a result, the upper surface of the reference electrode RE maycorrespond to the collection point for the first fluid FL1. In a pixelarea PA, since two reference electrodes RE overlap two portions of thebarrier wall WL, which are located at two end portions of the pixel areaPA, two sets of the first fluid FL1 are gathered to two areas adjacentto the two portions of the barrier walls WL, i.e., the two end portionsof the pixel area PA. When the first fluid FL1 is completely pushed tothe barrier wall WL and overlaps the reference electrode RE, the firstfluid FL1 may have a drop shape (at least in the cross-sectional view ofthe electrowetting display device) as illustrated by a hatched dropshape in FIG. 4B. The first fluid FL1 has the maximum height of thefirst fluid FL1 when the pixel PXL is in the ON-state.

When the difference between the voltage applied to the first electrodeEL1 and each of the voltages applied to the reference electrode RE andthe second electrode EL2 returns to about zero volts and/or is below athreshold value, the pixel PXL returns to an OFF-state. Theelectrowetting display device discussed with reference to FIGS. 4A and4B may have advantages and effects analogous to advantages and effectsof the electrowetting display device discussed with reference to FIGS.3A and 3B.

FIG. 5A is a plan view illustrating an electrowetting display deviceaccording to one or more embodiments of the present invention, and FIG.5B is a cross-sectional view taken along a line IV-IV′ indicated in FIG.5A.

Referring to FIGS. 5A and 5B, the pixel PXL includes (a portion of) anarray substrate, (a portion of) an opposite substrate, andelectrowetting layer fluids, e.g., a first fluid FL1 and a second fluidFL2. The array substrate includes a first base substrate BS1, a firstelectrode EL1, a first reference electrode RE1, a second referenceelectrode RE2, a switching device (not shown), a barrier wall WL, apartition wall PTN, a protrusion PRT, and a hydrophobic layer HPL. Abarrier layer BRL is disposed between the first base substrate BS1 andthe hydrophobic layer HPL and between the first base substrate BS1 andthe barrier wall WL. The opposite substrate includes a second basesubstrate BS2, a second electrode EL2, and a column spacer CS. The firstelectrode EL1, the first reference electrode RE1, the second referenceelectrode RE2, the switching device, and the second electrode EL2 mayserve as an electronic device configured to drive the electrowettinglayer fluids FL1 and FL2.

The protrusion PRT may protrude from the barrier layer BRL and/or may bedisposed on the barrier layer BRL, as illustrated in FIG. 5B. Aprotrusion PRT is disposed in each sub-pixel area. As illustrated inFIG. 5A, one protrusion PRT is disposed in each of the first sub-pixelarea SPA1 and the second sub-pixel area SPA2. The protrusion PRT extendssubstantially parallel to at least a side of the pixel area PA andextends substantially parallel to the partition wall PTN. The protrusionPRT has a height lower than that of the first fluid FL1 when the firstfluid FLI substantially completely covers the first sub-pixel area SPA1and the second sub-pixel area SPA2 while the pixel PXL is in theOFF-state. The hydrophobic layer HPL is disposed on the barrier layerBRL to cover the protrusion PRT. Accordingly, the protrusion HPL has ahydrophobic surface due to the hydrophobic layer HPL.

An electronic device is provided in each pixel PXL and applies anelectric potential difference between the EL1 and EL2 to control theelectrowetting layer fluids FL1 and FL2.

Among the parts of the electronic device, the first electrode EL1, thefirst reference electrode RE1, and the second reference electrode RE2are disposed on the first base substrate BS1, and the second electrodeEL2 is disposed on the second base substrate BS2.

The first electrode EL1 is disposed between the first base substrate BS1and the hydrophobic layer HPL and covers a portion of the firstsub-pixel area SPA1 and a portion of the second sub-pixel area SPA2. Inthe plan view of the electrowetting display device, the first electrodeEL1 has a rectangular shape, which may be similar to the shape of thepixel area PA, and two end portions of the first electrode EL1 in alongitudinal direction (or length direction of the pixel area PA) arespaced from the barrier wall WL. Two end portions the first electrodeEL1 in a width direction of the pixel area PA (perpendicular to thelength direction of the pixel area PA) overlap the barrier wall WL, asillustrated in FIG. 5A.

As illustrated in FIG. 5A, the first electrode EL1 may be integrallyformed as a single unitary unit disposed in the first sub-pixel areaSPA1 and the second sub-pixel area SPA2.

As illustrated in FIG. 5A, the first reference electrode REI is spacedapart from the first electrode EL1 and provided in the opening formedthrough the first electrode EL1. The second reference electrode RE2 isspaced apart from the two end portions of the first electrode EL1 in thelongitudinal direction and may contact and/or overlap the barrier wallWL.

The reference electrodes RE1 and RE2 are electrically insulated from thefirst electrode EL1 and are individually applied with a referencevoltage that may be independent of the voltage applied to the firstelectrode EL1. The reference voltage applied to each of the referenceelectrodes RE1 and RE2 has a level that is substantially equal to levelof the common voltage applied to the second electrode EL2. Accordingly,there may be substantially no electric potential difference betweeneither of the reference electrodes RE1 and RE2 and the second electrodeEL2.

The reference electrodes RE1 and RE2 are disposed on the same layer asand formed of the same material as the first electrode EL1.

When the pixel PXL is in the ON-state, a voltage different from thecommon voltage is applied to the first electrode EL1, and thus anelectric potential difference occurs between the first electrode EL1 andthe second electrode EL2, between the first electrode EL1 and the firstreference electrode RE1, and between the first electrode EL1 and thesecond reference electrode RE2. An attraction force acts between thesecond fluid FL2 and the first electrode EL1, and the second fluid FL2moves to the first electrode EL1 to push away the first fluid FL1. Inthe area in which the protrusion PRT is disposed (which may be referredto as a breaking point), the second fluid FL2 may easily push away thefirst fluid FL1 since a distance between the second fluid FL2 and thesurface of the protrusion PRT is short. Accordingly, the second fluidFL2 pushes away the first fluid FL1 from the area in which theprotrusion PRT is formed, i.e., from the breaking point, and the firstfluid FL1 moves away from sides of the protrusion PRT. In order toprecisely control the directions to which the fluids FL1 and FL2 move,breaking points may be spaced from the collection points in the subpixelareas. In one or more embodiments, the protrusion PRT is located at amidpoint position between the first reference electrode RE1 and thesecond reference electrode RE2, which is most far away from both thereference electrodes RE1 and RE2. The pushed first fluid FL1 is gatheredat areas overlapping the first reference electrode RE1 and the secondreference electrode RE2.

In an electrowetting display device having the structures discussed withreference to FIGS. 5A and 5B, movement and restitution of the fluids maybe substantially efficient since the breaking points and the collectionpoints of the fluids FL1 and FL2 are controlled using the protrusionPRT. Thus, the response speeds of the ON- and OFF-states of the pixelmay be satisfactorily fast, and nonclosing of the first fluid FL1 may beprevented. Advantageously, reproducibility and quality of the displayedimages may be satisfactory.

FIG. 6A is a plan view illustrating an electrowetting display deviceaccording to one or more embodiments of the present invention, and FIG.6B is a cross-sectional view taken along a line V-V′ indicated in FIG.6A. FIGS. 6A and 6B illustrate that at least a protrusion is positionedadjacent to the barrier wall WL and/or contacts the barrier wall WL. InFIGS. 6A and 6B, the same reference numerals may denote elements thatare analogous to or identical to elements illustrated in FIGS. 3A and3B, and thus detailed descriptions of the analogous or identicalelements may be omitted.

Referring to FIGS. 6A and 6B, the pixel PXL includes (a portion of) anarray substrate, (a portion of) an opposite substrate, andelectrowetting layer fluids, e.g., a first fluid FL1 and a second fluidFL2. The array substrate includes a first base substrate BS1, a firstelectrode EL1, a reference electrode RE, a switching device (notillustrated), a barrier wall WL, a partition wall PTN, a protrusion PRT,and a hydrophobic layer HPL. A barrier layer BRL is provided between thefirst base substrate BS1 and the hydrophobic layer HPL and between thefirst base substrate BS1 and the barrier wall WL. The opposite substrateincludes a second base substrate BS2, a second electrode EL2, and acolumn spacer CS. The first electrode EL1, the reference electrode RE,the switching device, and the second electrode EL2 may serve as anelectronic device configured to drive the electrowetting layer fluidsFL1 and FL2.

The protrusion PRT may protrude from the barrier layer BRL and/or may bedisposed on the barrier layer BRL, as illustrated in FIG. 6B. Aprotrusion PRT is disposed in each sub-pixel area and is disposedadjacent to the barrier wall WL corresponding to the short sides of thepixel area PA. The protrusion PRT may contact with barrier wall WL ormay be integrally formed with the barrier wall WL. As illustrated inFIG. 6A, the protrusion PRT extends parallel to at least a portion ofthe barrier wall WL.

The protrusion PRT has a height lower than that of the first fluid FL1when the first fluid FL1 substantially completely covers the firstsub-pixel area SPA1 and the second sub-pixel area SPA2 while the pixelPXL is in the OFF-state. The hydrophobic layer HPL is disposed on thebarrier layer BRL to cover the protrusion PRT. Accordingly, theprotrusion HPL has a hydrophobic surface due to the hydrophobic layerHPL.

An electronic device is provided in each pixel PXL and applies anelectric potential difference between the electrodes EL1 and EL2 tocontrol the electrowetting layer fluids FL1 and FL2.

Among the parts of the electronic device, the first electrode EL1 andthe reference electrode RE are disposed on the first base substrate BS1,and the second electrode EL2 is disposed on the second base substrateBS2.

The first electrode EL1 is disposed between the first base substrate BS1and the hydrophobic layer HPL and covers a portion of the firstsub-pixel area SPA1 and a portion of the second sub-pixel area SPA2.

The reference electrode RE is spaced from the first electrode EL1. Inone or more embodiments, as illustrated in FIG. 6A, the referenceelectrode RE is spaced from the first electrode EL1 and is located inthe opening formed through the first electrode EL1. The referenceelectrode RE is applied with the common voltage applied to the secondelectrode EL2.

When the pixel PXL is in the ON-state, a voltage different from thecommon voltage is applied to the first electrode EL1, and thus anelectric potential difference occurs between the first electrode EL1 andthe second electrode EL2 and between the first electrode EL1 and thereference electrode RE. The attraction force acts between the secondfluid FL2 and the first electrode EL1, and the second fluid FL2 moves tothe first electrode EL1 to push away the first fluid FL1. In the area inwhich the protrusion PRT is disposed, the second fluid FL2 may easilypush away the first fluid FL1 since a distance between the second fluidFL2 and the surface of the protrusion PRT is short. Accordingly, thesecond fluid FL2 pushes away the first fluid FL1 from the area in whichthe protrusion PRT is formed (wherein the area may be referred to as abreaking point), and the first fluid FL1 moves to an area overlappingthe reference electrode RE from the protrusion PRT. In order toprecisely control the directions to which the fluids FL1 and FL2 move,breaking points may be spaced from the collection points in thesub-pixel areas. The pushed first fluid FL1 is gathered on the referenceelectrode RE and is adjacent to (and contacts) the partition wall PTN.

In an electrowetting display device having the structures discussed withreference to FIGS. 6A and 6B, movement and restitution of the fluids maybe substantially efficient since the breaking points and the collectionpoints of the fluids FL1 and FL2 are controlled using the protrusionPRT. Thus, the response speeds of the ON- and OFF-states of the pixelmay be satisfactorily fast, and nonclosing of the first fluid FL1 may beprevented. Advantageously, reproducibility and quality of the displayedimages may be satisfactory.

FIG. 7 is a cross-sectional view illustrating an electrowetting displaydevice according to a one or more embodiments of the present invention,wherein the cross-sectional view may be taken along the line I-I′indicated in FIG. 1A.

Referring to FIG. 7, the pixel PXL includes (a portion of) an arraysubstrate, (a portion of) an opposite substrate, and electrowettinglayer fluids FL1 and FL2, e.g., a first fluid FL1 and a second fluidFL2. The array substrate includes a first base substrate BS1, a colorfilter CF, a first electrode EL1, a switching device (not shown), abarrier wall WL, a partition wall PTN, and a hydrophobic layer HPL. Aninsulating layer INS is disposed between the first base substrate BS1and the color filter CF, and a barrier layer BRL is disposed between thecolor filter CF and the hydrophobic layer HPL and between the colorfilter CF and the barrier wall WL.

The opposite substrate includes a second base substrate BS2, a secondelectrode EL2, and a column spacer CS. The first electrode EL1, theswitching device, and the second electrode EL2 may serve as anelectronic device configured to drive the electrowetting layers FL1 andFL2.

The color filter CF is used to enable the pixel PXL to display a color.In one or more embodiments, the color filter CF may have one of a redcolor, a green color, and a blue color. In one or more embodiments, thecolor filter CF may have one of various colors other than red, green,and blue. In one or more embodiments, the color filter may have a whitecolor. A white W color that transmits all wavelengths of the white lightpassing therethrough may be used to improve brightness, and the colorfilter CF may have one or the red color, the green color, the bluecolor, and the white color. In one or more embodiments, the color filterCF may have on of a yellow color, a cyan color, and a magenta color. Theyellow color, the cyan color, the magenta color may be used in additionto the red, green, blue, and white colors or may be used instead of atleast one of the red, green, blue, or white color.

Pixels corresponding to the red color filters, pixels corresponding tothe green color filters, pixels corresponding to the blue color filters,and pixels corresponding to the white color filters are referred to asred pixels RP, green pixels GP, blue pixels BP, and whit pixels WP,respectively. One of the red pixels RP, one of the green pixels GP, oneof the blue pixels BP, and one of the white pixels WP may form a pixelunit PU, which is a minimum unit for displaying a color image. Theelectrowetting display device may include a plurality of pixel units PUarranged in a matrix form for displaying color images that may beperceived by a viewer.

In a pixel unit PU, the red pixel RP, the green pixel GP, the blue pixelBP, and the white pixel WP may be arranged in one of various ways. Theposition of the partition wall may depend on the arrangement of thecolor pixels.

FIGS. 8A to 8C are plan views illustrating arrangements of pixels andpositions of the partition wall. For the convenience of explanation, onepixel unit PU has been illustrated in each of FIGS. 8A to 8C.

Referring to FIG. 8A, the red pixel RP, the green pixel GP, the bluepixel BP, and the white pixel WP are arranged in two rows. The red pixelRP, the green pixel GP, and the blue pixel BP are arranged in a firstrow, and the white pixel WP is arranged in a second row. The red pixelRP, the green pixel GP, and the blue pixel BP extend in a columndirection and are arranged in a row direction. The white pixel WPextends in the row direction. In each of the red pixel RP, the greenpixel GP, the blue pixel BP, and the white pixel WP, a partition wallPTN extends in a direction substantially vertical to the direction inwhich the red pixel RP, the green pixel GP, the blue pixel BP, and thewhite pixel WP extend. That is, the partition wall PTN in each of thered pixel RP, the green pixel GP, and the blue pixel BP extends in therow direction. The partition wall PTN in the white 5 pixel WP extends inthe column direction.

Referring to FIG. 8B, the red pixel RP, the green pixel GP, the bluepixel BP, and the white pixel WP are arranged in a matrix form of onerow by four columns. The red pixel RP, the green pixel GP, the bluepixel BP, and the white pixel WP extend in the column direction and aresequentially arranged in the row direction. In each of the red pixel RP,the green pixel GP, the blue pixel BP, and the white pixel WP, apartition wall PTN extends in the row direction substantially verticalto the direction in which the red pixel RP, the green pixel GP, the bluepixel BP, and the white pixel WP extend.

Referring to FIG. 8C, the red pixel RP, the green pixel GP, the bluepixel BP, and the white pixel WP are arranged in a matrix form of tworows by two columns. The red pixel RP and the blue pixel BP are arrangedin a first row, and the green pixel GP and the white pixel WP arearranged in a second row. In one or more embodiments, each of the redpixel RP, the green pixel GP, the blue pixel BP, and the white pixel WPhas a square shape, and the partition wall PTN in each of the pixelsextends in the column or row direction to be substantially in parallelto one of sides of the corresponding one of the red pixel RP, the greenpixel GP, the blue pixel BP, and the white pixel WP.

FIG. 9A is a plan view illustrating the electrowetting display device infurther detail according to one or more embodiments of the presentinvention, and FIG. 9B is a cross-sectional view taken along a lineVI-VI′ indicated in FIG. 9B. The electrowetting display device discussedwith reference to FIGS. 9A and 9B may have features and advantages thatare analogous to or identical to the electrowetting display devicediscussed with reference to FIGS. 3A and 3B.

Referring to FIGS. 9A and 9B, the electrowetting display device includesthe array substrate, the opposite substrate overlapping the arraysubstrate, and the electrowetting layer fluids, e.g., the first fluidFL1 and the second fluid FL2, disposed between the array substrate andthe opposite substrate.

The array substrate includes the first base substrate BS1, the linepart, the first electrode EL1, the reference electrode RE, the switchingdevice, the storage electrode STE, the barrier wall WL, the partitionwall PTN, and the hydrophobic layer HPL.

The first base substrate BS1 has the rectangular shape with a pair oflong sides and a pair of short sides.

The line part applies signals to the switching devices and includes aplurality of gate lines GL, a plurality of data lines DL, and a storagelines STL.

The gate lines GL extend in the row direction on the first basesubstrate BS1. The data lines DL extend in the column direction crossingthe row direction. The data lines DL are disposed on the first basesubstrate BS1 on which the gate lines GL are disposed. A gate insulatinglayer GI is disposed between the gate lines GL and the data lines DL.The storage lines STL extend substantially in parallel to the gate linesGL and are spaced apart from the gate lines GL. Each storage line STLincludes a first storage line STL1 and a second storage line STL2adjacent to the first storage line STL 1 with a corresponding gate lineof the gate lines GL being disposed therebetween.

The switching device is connected to a corresponding one of the gatelines GL and a corresponding one of the data lines DL. The switchingdevice may be, but not limited to, a transistor TR configured to includea gate electrode GE, a semiconductor layer SM, a source electrode SE,and a drain electrode DE.

The gate electrode GE protrudes from the corresponding gate line GL.

The semiconductor layer SM is disposed on the gate electrode GE with thegate insulating layer GI being disposed therebetween. The semiconductorlayer SM is formed of one or more of oxide semiconductor, amorphoussilicon semiconductor, and crystalline or polycrystalline siliconsemiconductor. The gate insulating layer GI is formed on the first basesubstrate BS1 on which the gate line GL and the gate electrode areformed to cover the gate line GL and the gate electrode GE.

The semiconductor layer SM includes an active layer disposed on the gateinsulating layer GI and an ohmic contact layer disposed on the activelayer. The active layer overlaps the source electrode SE and the drainelectrode DE and overlaps an area between the source electrode SE andthe drain electrode DE. The ohmic contact layer is provided between theactive layer and the source electrode SE and between the active layerand the drain electrode DE.

The source electrode SE is branched from the corresponding data line ofthe data line DL, and the drain electrode DE is spaced apart from thesource electrode SE with the gate electrode GE being disposedtherebetween. The source electrode SE and the drain electrode DEpartially overlap the gate electrode GE. The drain electrode DE overlapsthe first storage line STL1.

In one or more embodiments, the source electrode SE and the drainelectrode DE overlap a portion of the semiconductor layer SM in an areaexcept for the area between the source electrode SE and the drainelectrode DE. The area between the source electrode SE and the drainelectrode DE serves as a channel portion, and an upper surface of theactive layer is exposed through the area between the source electrode SEand the drain electrode DE. When the transistor TR is turned on, acurrent may flow between the source electrode SE and the drain electrodeDE through the channel portion.

A passivation layer PSV is disposed on the channel portion to cover thechannel portion, so that the channel portion is protected by thepassivation layer PSV.

The storage electrode STE overlaps the source electrode SE with thechannel portion being disposed therebetween. When the transistor TR isturned on, the storage electrode STE is electrically connected to thesource electrode SE through the channel portion. The storage electrodeSTE overlaps the second storage line STL2.

The first electrode EL1 is connected to the drain electrode DE through afirst contact hole CH1 with the passivation layer PSV being disposedtherebetween.

The first contact hole CH1 is formed through the passivation layer PSV,and a portion of the drain electrode DE is exposed through the firstcontact hole CHI. The first electrode EL1 is electrically connected tothe exposed portion of the drain electrode DE.

The first electrode EL1 may be integrally formed as a single unitaryunit and provided with a through opening, which corresponds to the areain which the partition wall PTN is formed.

The reference electrode RE is disposed in the opening. The referenceelectrode RE covers (or over laps) the transistor TR and a portion ofthe first storage line STL1 and the second storage line STL2. Thereference electrode RE is spaced from the first electrode EL1 and isconnected to the second storage line STL2 through a second contact holeCH2 with the passivation layer PSV being disposed therebetween.

The second contact hole CH2 is formed through the passivation layer PSVand the gate insulating layer GI to expose a portion of the secondstorage line STL2. The reference electrode RE is electrically connectedto the exposed portion of the second storage line STL2 through thesecond contact hole CH2.

The storage lines STL1 and STL2 are applied with the reference voltage.The reference voltage may be the same as the common voltage applied tothe second electrode EL2.

Although not illustrated in FIGS. 9A and 9B, a color filter (not shown)may be disposed between the drain electrode DE and the passivation layerPSV. The color filter is used to enable the pixel to display a color.The color filter may have one or more features discussed with referenceto FIGS. 7, 8A, 8B, and 8C.

The barrier layer BRL is disposed on the first base substrate BS1 onwhich the first electrode EL1 is formed. The barrier layer BRL preventsa portion of the electrowetting layer fluids FL1 and FL2, e.g., amaterial having a polarity or an electrical conductivity, fromcontacting the first electrode EL1 by diffusion or infiltration. This isto prevent the first electrode EL1 from being affected or damaged by thematerial having the polarity or the electrical conductivity in theelectrowetting layer fluids FL1 and FL2.

The barrier wall WL and the partition wall PTN are disposed on the firstbase substrate BS1 on which the barrier layer BRL is formed. The barrierwall WL and the partition wall PTN may protrude with respect to thefirst base substrate BS1. A space surrounded by the first base substrateBS1 and the barrier wall WL is defined in each pixel area PA. Thepartition wall PTN partitions the pixels area PA into the sub-pixelareas, e.g., the sub-pixel areas SPA1 and SPA2, and restricts themovement of at least one of the first fluid FL1 or the second fluid FL2in the sub-pixel areas SPA1 and SPA2.

The partition wall PTN may overlap a gate line GL, a portion of thebarrier wall WL may overlap a data line DL, and a portion of the barrierwall WL may overlap a gate line GL.

The hydrophobic layer HPL covers (and/or overlaps) the pixel area PA ofthe first base substrate BS1.

The opposite substrate includes the second base substrate BS2overlapping the first base substrate BS1 and includes the secondelectrode EL2.

The column spacer CS is disposed on the second base substrate BS2 andprotrudes with respect to the second base substrate BS2. The columnspacer CS is disposed at a position corresponding to the barrier wall WLto allow a contact surface thereof to directly contact the barrier wallWL, and thus the column spacer CS maintains a distance (or cell gap)between the first base substrate BS1 and the second base substrate BS2in cooperation with the barrier wall WL.

FIG. 10A is a plan view illustrating the electrowetting display devicein further detail according to one or more embodiments of the presentinvention, and FIG. 10B is a cross-sectional view taken along a lineVII-VII′ indicated in FIG. 10B. The electrowetting display devicediscussed with reference to FIGS. 10A and 10B may have features andadvantages that are analogous to or identical to the electrowettingdisplay device discussed with reference to FIGS. 4A and 4B.

Referring to FIGS. 10A and 10B, the electrowetting display deviceincludes the array substrate, the opposite substrate overlapping thearray substrate, and the electrowetting layer fluids, e.g., the firstfluid FL1 and the second fluid FL2 disposed between the array substrateand the opposite substrate.

The array substrate includes the first base substrate BS1, the linepart, the first electrode EL1, the reference electrode RE, the switchingdevice, the storage electrode STE, the barrier wall WL, the partitionwall PTN, and the hydrophobic layer HPL.

The line part applies signals to the switching devices and includes aplurality of gate lines GL, a plurality of data lines DL, and a storagelines STL.

The gate lines GL extend in the row direction on the first basesubstrate BS1.

The data lines DL extend in the column direction crossing the rowdirection. The data lines DL are disposed on the first base substrateBS1 on which the gate lines GL are disposed with the gate insulatinglayer GI being disposed between the gate lines GL and the data lines DL.

The storage lines STL extend substantially in parallel to the gate linesGL and spaced apart from the gate lines GL. Each storage line STLincludes the first storage line STL1 and the second storage line STL2adjacent to the first storage line STL1 with a corresponding gate lineof the gate lines GL being disposed therebetween. The first storage lineSTL1 is disposed adjacent to the gate line of a present stage, and thesecond storage line STL2 is disposed adjacent to the gate line of aprevious stage. The first storage line STL1 and the second storage lineSTL2 are spaced from each other with the corresponding gate line GLbeing disposed therebetween.

The switching device is connected to a corresponding one of the gatelines GL and a corresponding one of the data lines DL. The switchingdevice may be, but not limited to, a transistor TR configured to includea gate electrode GE, a semiconductor layer SM, a source electrode SE,and a drain electrode DE.

The gate electrode GE protrudes from the corresponding gate line GL.

The semiconductor layer SM is disposed on the gate electrode GE with thegate insulating layer GI being disposed therebetween. The semiconductorlayer SM is formed of one or more of oxide semiconductor, amorphoussilicon semiconductor, and crystalline or polycrystalline siliconsemiconductor. The gate insulating layer GI is formed on the first basesubstrate BS1 on which the gate line GL and the gate electrode areformed to cover the gate line GL and the gate electrode GE.

The semiconductor layer SM includes an active layer disposed on the gateinsulating layer GI and an ohmic contact layer disposed on the activelayer. The active layer overlaps the source electrode SE and the drainelectrode DE and overlaps an area between the source electrode SE andthe drain electrode DE. The ohmic contact layer is provided between theactive layer and the source electrode SE and between the active layerand the drain electrode DE.

The source electrode SE is branched from the corresponding data line ofthe data line DL and the drain electrode DE is spaced apart from thesource electrode SE with the gate electrode GE being disposedtherebetween. The source electrode SE and the drain electrode DEpartially overlap the gate electrode GE. The drain electrode DE overlapsthe first storage line STL1.

In one or more embodiments, the source electrode SE and the drainelectrode DE overlap a portion of the semiconductor layer SM in an areaexcept for the area between the source electrode SE and the drainelectrode DE. The area between the source electrode SE and the drainelectrode DE serves as a channel portion, and an upper surface of theactive layer is exposed through the area between the source electrode SEand the drain electrode DE. When the transistor TR is turned on, acurrent may flow between the source electrode SE and the drain electrodeDE through the channel portion.

A passivation layer PSV is disposed on the channel portion to cover thechannel portion, so that the channel portion is protected by thepassivation layer PSV.

The storage electrode STE floats on (and overlaps) the gate insulatinglayer GI and overlaps the second storage line STL2.

The first electrode EL1 is connected to the drain electrode DE through afirst contact hole CH1 with the passivation layer PSV being disposedtherebetween. The first electrode EL1 is connected to the storageelectrode STE through a second contact hole CH2 with the passivationlayer PSV being disposed therebetween.

The first contact hole CH1 is formed through the passivation layer PSV,and the portion of the drain electrode DE is exposed through the firstcontact hole CH1. The first electrode EL1 is electrically connected tothe exposed portion of the drain electrode DE.

The second contact hole CH2 is formed through the passivation layer PSV,and a portion of the storage electrode STE is exposed through the secondcontact hole CH2. The first electrode EL1 is electrically connected tothe exposed portion of the storage electrode STE.

The first electrode EL1 may be integrally formed as a single unitaryunit. The first electrode EL1 is not disposed at two end portions of thepixel area PA in the longitudinal direction (or the length direction ofthe pixel area PA), and thus the first electrode EL1 is spaced from thebarrier wall.

The reference electrode RE is disposed to be spaced apart from the firstelectrode EL1. The reference electrode RE is spaced apart from both endportions of the first electrode EL1 in the longitudinal direction,overlaps the barrier wall WL, and overlaps the portion of the next pixelarea PA. The reference electrode RE is electrically connected to thesecond storage line STL2 through a third contact hole CH3.

The third contact hole CH3 is formed through the passivation layer PSVand the gate insulating layer GI to expose a portion of the secondstorage line STL2. The reference electrode RE is connected to theexposed portion of the second storage line STL2 through the thirdcontact hole CH3.

The storage lines STL1 and STL2 are applied with the reference voltage.The reference voltage may be the same as the common voltage applied tothe second electrode EL2.

Although not illustrated in FIGS. 10A and 10B, a color filter (notshown) may be disposed between the drain electrode DE and thepassivation layer PSV.

The barrier layer BRL is disposed on the first base substrate BS1 onwhich the first electrode EL1 is formed. The barrier layer BRL preventsa portion of the electrowetting layer fluids FL1 and FL2, e.g., amaterial having a polarity or an electrical conductivity, fromcontacting the first electrode EL1 by diffusion or infiltration.

The barrier wall WL and the partition wall PTN are disposed on the firstbase substrate BS1 on which the barrier layer BRL is formed. The barrierwall WL and the partition wall PTN may protrude with respect to thefirst base substrate BS1. A space surrounded by the first base substrateBS1 and the barrier wall WL is defined in each pixel area PA. Thepartition wall PTN partitions the pixels area PA into the sub-pixelareas, e.g., the sub-pixel areas SPA1 and SPA2, and restricts themovement of at least one of the first fluid FL1 or the second fluid FL2in the sub-pixel areas SPA1 and SPA2.

The partition wall PTN is disposed on the first electrode EL1. A portionof the barrier wall WL overlaps the gate line GL adjacent to the pixelPXL, and another portion of the barrier wall WL overlaps the data lineDL adjacent to the pixel PXL.

The hydrophobic layer HPL covers (and/or overlaps) the pixel area PA ofthe first base substrate BS1.

The opposite substrate includes the second base substrate BS2overlapping the first base substrate BS1 and includes the secondelectrode EL2.

The column spacer CS is disposed on the second base substrate BS2 andprotrudes with respect to the second base substrate BS2. The columnspacer CS is disposed at a position corresponding to the barrier wall WLto allow a contact surface thereof to directly contact the barrier wallWL, and thus the column spacer CS maintains a distance (or cell gap)between the first base substrate BS1 and the second base substrate BS2in cooperation with the barrier wall WL.

In the electrowetting display devices illustrated in FIGS. 9A, 9B, 10A,and 10B, a data voltage applied to the first electrode (while theswitching device is operated) is transmitted by the data line. When thegate signal is applied to the gate line, the transistor is turned on,and the data voltage applied to the data line is applied to the firstcapacitor and the second capacitor. After the data voltage is applied tothe first electrode, the data voltage remains in the capacitors for apredetermined time period due to the coupling capacitance of each of theelectrowetting capacitor and the storage capacitor so as to maintain thestate of the pixel until the data voltage is refreshed. Here, thestorage capacitor includes a capacitor formed by the drain electrode,the insulating layer, and the first storage line, a capacitor formed bythe storage electrode, the insulating layer, and the second storageline, and a capacitor formed by the storage electrode, the passivationlayer, and the reference electrode.

In one or more embodiments, the electrowetting display device is atransmission type electrowetting display device, and the collectionpoint of the first fluid may be controlled to be disposed on the area inwhich the transistor and the storage line are formed so as to providesatisfactory transmittance. An electric field may be generated by thetransistor, and the movement of the first fluid may be disturbed by theelectric field if the electric field is not blocked. According to theone or more embodiments, the reference electrode is disposed on the areain which the transistor is formed, and thus the electric field isblocked. Thus, satisfactory transmittance may be provided withoutreduction of aperture ratio, and the first fluid is prevented frommalfunctioning Advantageously, satisfactory image display quality may beprovided.

Although the embodiments of the present invention have been described,it is understood that the present invention should not be limited tothese embodiments. Various changes and modifications can be made by oneordinary skilled in the art within the spirit and scope of the presentinvention as hereinafter claimed.

For instance, the first electrode and the second electrode arerespectively disposed on the first base substrate and the second basesubstrate in the example electrowetting display devices, but they shouldnot be limited thereto or thereby. In one or more embodiments, the firstelectrode and the second electrode may be both disposed on only one ofthe first base substrate and the second base substrate. In one or moreembodiments, the first electrode and the second electrode may have oneor more shapes that are different from the shapes discussed in theexample embodiments.

Although the embodiments of the present invention have been individuallydescribed, features of the embodiments may be combined unless theircoexistence is impossible.

What is claimed is:
 1. An electrowetting display device comprising: afirst substrate and a second substrate; a first pixel and a second pixelbetween the first substrate and the second substrate, wherein the firstpixel and the second pixel each include pixel portions, and wherein eachpixel portion includes a first fluid and a second fluid immiscible withthe first fluid, the second fluid having an electrical conductivity or apolarity; pixel walls disposed on the first substrate and at leastpartially separating the pixel portions from one another; a firstelectrode disposed on the first substrate, wherein the first electrodeis electrically coupled to the pixel portions of the first pixel; asecond electrode disposed on the first substrate, wherein the secondelectrode is electrically coupled to the pixel portions of the secondpixel; and a third electrode disposed on the second substrate, whereinthe third electrode is electrically coupled to the pixel portions of thefirst pixel and the second pixel.
 2. The electrowetting display deviceof claim 1, further comprising: an electronic driving device configuredto provide voltages to the pixel portions of the first pixel and thesecond pixel via the first electrode, the second electrode, and thethird electrode, wherein the third electrode is configured to apply acommon voltage to generate an electric field in cooperation with thefirst electrode or the second electrode.
 3. The electrowetting displaydevice of claim 1, wherein each of the pixel portions occupies arectangular shaped area, and wherein the pixel walls are substantiallyparallel to one of four sides of the rectangular shaped areas of thepixel portions.
 4. The electrowetting display device of claim 3, furthercomprising a barrier wall that partitions the first pixel from thesecond pixel, wherein at least one pixel portion of the first pixel andat least one pixel portion of the second pixel are adjacent to oneanother and partitioned from each other by the barrier wall.
 5. Theelectrowetting display device of claim 3, wherein the first fluid ineach of the pixel portions are identical to one another.
 6. Theelectrowetting display device of claim 1, wherein the third electrodeoverlaps at least a portion of the pixel walls when viewed in a planview.
 7. The electrowetting display device of claim 1, furthercomprising a barrier wall that partitions the first pixel from thesecond pixel, wherein the third electrode overlaps at least a portion ofthe barrier wall when viewed in a plan view.
 8. The electrowettingdisplay device of claim 1, further comprising: a switching device ineach of the first pixel and the second pixel; gate lines extending in afirst direction and being capable of providing a gate voltage to gateelectrodes of the switching device in each of the first pixel and thesecond pixel; and data lines extended in a second directionsubstantially perpendicular to the first direction and being capable ofproviding a data voltage to source electrodes of the switching device ineach of the first pixel and the second pixel.
 9. The electrowettingdisplay device of claim 8, wherein the gate lines overlap at least aportion of the pixel walls when viewed in a plan view.
 10. Theelectrowetting display device of claim 8, further comprising a firststorage line extending in the first direction and spaced apart from thegate lines to form a capacitor together with a drain electrode of theswitching device.
 11. The electrowetting display device of claim 10,further comprising a second storage line disposed adjacent to the firststorage line, wherein the first storage line or the second storage lineis connected to the third electrode.
 12. The electrowetting displaydevice of claim 1, wherein at least a portion of the pixel walls arehydrophilic.
 13. The electrowetting display device of claim 1, furthercomprising: a barrier layer disposed on the first substrate; and aprotrusion disposed on the barrier layer in each of the pixel portions,wherein the protrusion protrudes upward from the first substrate. 14.The electrowetting display device of claim 13, wherein the protrusionoverlaps with at least a portion of the pixel walls.
 15. Theelectrowetting display device of claim 14, wherein the protrusion isintegrally formed with at least a portion of the pixel walls.
 16. Theelectrowetting display device of claim 1, further comprising: a firstcolor filter in the first pixel that covers all of the pixel portions ofthe first pixel; and a second color filter in the second pixel thatcovers all of the pixel portions of the second pixel.
 17. Anelectrowetting display device comprising: a first substrate and a secondsubstrate; a first pixel and a second pixel separated from each other byfirst pixel walls on the first substrate, wherein the first pixel ispartitioned by second pixel walls into two or more first pixel portionsand the second pixel is partitioned by the second pixel walls into twoor more second pixel portions, and wherein the first pixel and thesecond pixel each include a first fluid and a second fluid immisciblewith the first fluid, the second fluid having an electrical conductivityor a polarity; a first electrode disposed on the first substrate,wherein the first electrode is electrically coupled to the first pixelportions; a second electrode disposed on the first substrate, whereinthe second electrode is electrically coupled to the second pixelportions; and a third electrode disposed on the second substrate,wherein the third electrode is electrically coupled to the first and thesecond pixel portions.
 18. The electrowetting display device of claim17, further comprising: a barrier layer disposed on the first substrate;and a protrusion disposed on the barrier layer in each of the first andthe second pixel portions, wherein the protrusion protrudes upward fromthe first substrate.
 19. The electrowetting display device of claim 18,wherein the protrusion overlaps with at least a portion of the secondpixel walls.
 20. The electrowetting display device of claim 19, whereinthe protrusion is integrally formed with at least a portion of thesecond pixel walls.